Da big bang

**PBI** · 10-01-2008, 13:02

As far as I'm aware it's inclusive, but it's not my specialism. I find astronomy interesting, certainly, and I took a few modules in it in my undergraduate degree, but I am very definitely a physicist and not an astronomer. I mostly know about scattering processes and quantum mechanics, with a healthy dollop of relativity thrown in for good measure.

So I certainly wouldn't claim to be more knowledgeable than you on astronomy, and as far as I'm aware your summary of the known features making up our surroundings in space is a pretty good one, but the problem is it does not address my earlier points, which pertain to the nature of Compton scattering on a more fundamental level.

It doesn't especially matter what particular structures or media are responsible for the Compton scattering, the point is that I simply cannot see how sufficient Compton scattering could occur to introduce a signficant redshift without also introducing a random (in the true, quantum mechanical sense of the word) deflection of the direction of the light which would make it impossible to observe clearly defined structures such as galaxies.

**cmacq** · 10-02-2008, 00:32

Originally Posted by Poor Bloody Infantry

It doesn't especially matter what particular structures or media are responsible for the Compton scattering, the point is that I simply cannot see how sufficient Compton scattering could occur to introduce a signficant redshift without also introducing a random (in the true, quantum mechanical sense of the word) deflection of the direction of the light which would make it impossible to observe clearly defined structures such as galaxies.

Right, more to your field.

Poor Bloody Infantry; second question

When we say Compton scattering, given light's nature, do we mean an actual particle deflection, the increase of wavelengths, or due to duality, an alteration in the resonance of quantum fields (with an added decrease in velocity)? Just addressing the attributes of the observation and although I know its important, I’m purposely leaving out the fact that the light has a given velocity.

CmacQ

**Papewaio** · 10-02-2008, 01:50

IMDHO from what I can vaguely recollect.

Compton scattering is the change in energy of the photon due to interaction with matter.

Now as it is a photon it only travels at the speed of light. It doesn't slow down. Therefore if it loses energy it will have to change its wavelength/frequency. So as it loses energy it redshifts.

With Compton scattering the change in energy is in proportion to the change in direction. So any Compton scattering red shift will cause a change in its direction. This scattering is not uniform like that of light refraction, so unlike a rainbow if you scatter all the photons from an object it will be blurred at best. Compton shifted light will both be randomly scattered (blurry) and as such have different red shifts (you'd get a redshifted hump for the spectroscopic lines rather then a relativistic redshifted bright line)

Also at the visible wavelengths instead of Compton scattering the photons could just as likely be causing the photoelectric effect with the matter they are interacting with. So instead of even being randomly scattered and red shifted, the light problem will just ionise the local matter and stop there.

So if any great degree of Compton scattering was going to occur it would:
a) Leave blurry pictures
b) Have a redshift 'hump' of the spectroscopic lines
c) Leave little in the visible light spectrum to see because of the photoelectric effect.

In short you would see the stars in the infra-red spectrum if at all, and they would be blurry blobs.

**cmacq** · 10-02-2008, 05:42

Sorry,

I may be completely wrong, and my argument may by now be clear, but I'm headed somewhere with my setup and questions.

The point is in a nutshell, that in the controlled environment of the lab, the Compton Effect is observed when the photon is in motion, while the target matter it impacts is relatively static and thus any motion on its part, is indeed random. Thus, the directional deflection of the photon is also random, and we have scattering. In contrast, in the ultimately larger context, the target matter belongs to specific features and/or structures, such as those outlined above. This matter is indeed not static, nor is its motion radom, as it has a relatively common nonrandom velocity and directional motion within each of the given features and/or structures. Thus, as incoming photons pass through these specific features and/or structures and strike matter, some visual distortion may occur, yet directional defection is relatively uniform, in much the same manner, as when light passes through earth’s atmosphere? Now if space were an entirely empty void, this certainly would not be the case, and the observation would indeed be the result of the Doppler Effect, however space is not empty?

CmacQ

**Papewaio** · 10-07-2008, 05:14

Photons are always moving at the speed of light. The speed of matter unless also moving close to the speed of light would not matter (no pun intended). I'm not sure if matter moving at relativistic speeds has an impact on the Compton equations (again no pun intended).

Also as noted above because the deflection would not be uniform this would mean that he spectra would be blurred. Rather then just shifted to the red. The lines would be fatter and dimmer because of Compton scattering. Refraction in the atmosphere has a uniform angle change. Also some of the spectra would be absorbed depending on the matter encountered (this is how the Greenhouse effect works).

Also matter at all times is moving and random in motion unless it has a temperature of 0 Kelvin. This is lower then the background radiation of the observed Universe (something like 3 Kelvin). As long as matter has a temperature above 0 kelvin then matter moves, that is what heat is.

**cmacq** · 10-07-2008, 06:16

Originally Posted by Papewaio

Photons are always moving at the speed of light. The speed of matter unless also moving close to the speed of light would not matter (no pun intended). I'm not sure if matter moving at relativistic speeds has an impact on the Compton equations (again no pun intended).

Indeed, to tell the truth, neither do I. However, that is the question. Several lines of evidence might suggest that it does.

CmacQ

**Viking** · 10-07-2008, 13:13

Originally Posted by Papewaio

Now as it is a photon it only travels at the speed of light. It doesn't slow down. Therefore if it loses energy it will have to change its wavelength/frequency. So as it loses energy it redshifts.

According to a wiki article, the speed of light in water is 0.75 c. I'm not sure about the validity of that velocity, but the fact that the speed of light depends on the medium is the cause of Cherenkov radiation. Photons do not have any mass; such that the velocity would not really matter for the energy?

Since space is not a perfect vacuum, one would assume that even in the so called vacuum of space; light does not travel at a constant speed?

Of course, none of this appear to have any relevance to the debate at hand (a debate which is a bit beyond me).

**Old Geezer** · 02-16-2009, 06:02

Big Bang Theories are philosophical/religious theories and have no basis in demonstrable scientific facts, but rather contradict science and logic to such an extent as to be patently silly.